Recreational boating is a large industry in this country. Many people own a boat which is used for fishing, sightseeing, water skiing, or other recreational pursuits. Some boats are docked permanently in a marina or at some other permanent dock. However, many people have their boats in water only when the boat is in use. Consequently, the boat may be launched at a boat launch ramp from a trailer or other transport device when it is desired to use the boat and the boat replaced on the trailer after the use of the boat is complete.
Some recreational boaters are fortunate enough to live directly on navigable water. Ordinarily, the people who live on navigable water and use a boat will have a dock of some kind, usually a floating dock connected to the land where they may moor their boat while getting in and out of the boat and before and after use. However, leaving the boat in water creates problems of various kinds. First, marine organisms, vegetation, and the like may grow on the bottom of the boat, which can either damage the boat or certainly decrease the efficiency of the boat while passing through the water, thus slowing the overall performance of the boat. Second, if the boat is in a waterway where other boats pass, these boats may create wakes which can wash the moored boat into the dock or other structure, damaging both the structure and the boat. Consequently, most docks are equipped with various kinds of fenders, which may be old tires, inflatable rubber bladders, or the like. A variety of other expedients are employed, such as extendable whip mooring devices which hold the boat a predetermined distance away from the mooring structure to reduce the potential damage to the boat and to the dock from wakes, wave action, wind, or currents. However, these expedients still leave the boat in the water with possible damage from marine organisms which may attach themselves to the hull of the boat while it is submerged in the water.
Consequently, many people who have a floating dock on navigable water will use a boat lift to protect their boat from wave and wake action, as well as from marine organisms. A boat lift ordinarily consists of a set of pilings. Secured on these pilings is a structure which is heavier than water, which has a set of rails on which the hull of the boat may rest. The structure supporting the rails is ordinarily attached by pulleys to at least one cable, which is connected to a reel and an electric motor. The reel acts like a winch to extend or retract the cable. As the cable extends, it lowers the structure relative to the pilings and as the cable retracts, it raises the structure relative to the pilings. The pilings, structure, cable, and winch will be rated for a particular weight, which will be the dry weight of the boat for which the lift is proposed to be used. To use the lift, the supporting structure is lowered in the water by unwinding the cable from the reel. The user then guides or pilots the boat onto the rails or other supporting structure and then activates the winch to rewind the cable, thus lifting the structure with the boat now supported by the structure. The cable is continued to be rewound until the boat is entirely lifted out of the water. This accomplishes two desirable outcomes. First, the hull of the boat is no longer exposed to marine organisms in the water. Secondly, because the boat is no longer in water, wave or wake action will not affect the boat, so it will be secured against damage from impacts caused by the wave, current, or wake action.
For both ease of construction and economy of construction, most boat lifts simply have a structure that is lowered into the water and sinks in the water from the force of gravity. The structure is lifted and lowered by the flexible, albeit inelastic cables. Typically, only one or two cables are used to lower and to raise the structure on which the boat rests. Moreover, because piloting a boat is not an exact science, the pilings on which the boat lift is supported are ordinarily substantially wider than the width or beam of the boat for which the lift is designed. Thus, the boat lift structure on which the boat is supported may move around if it is subject to forces in horizontal plane relative to the vertical direction of the lifting and lowering motion of the boat lift structure supported by the cables. Thus, as one maneuvers a boat onto a boat lift to be raised out of the water, there is a period of time where the boat is floating in the water. Hence, currents within the water, wind action on the boat, wakes, and the like can cause a boat to be moved in the horizontal plane. This is true, even after the lift has started operating, where the boat may be partially supported by the lift structure during the motor retracting the cable, but still within the water and subject to the force of wave or a boat wake. This period of time, where the boat is inside the pilings but not fully raised by the lift out of the water, can be dangerous both for operators of the boat and to the boat itself.
A variety devices have been proposed to overcome the difficulty of docking a boat, while not specifically proposed for a boat lift, that recognize that wind and current and rough water may exacerbate the difficulty of guiding a boat into a narrow area. For example, Capps U.S. Pat. No. 5,113,702 discloses vertical padded boat guards extending from the side walls of a dock. A boat slides between the vertical guards and is secured against padded stop members positioned toward the boat bow. Likewise, Ryan U.S. Pat. No. 5,911,189 discloses boat guides that are used for guiding a boat in and out of a boat slip. Having elongated tubular members, an axil is received coaxially within the tubular member with padding or at least space between the tubular member and the axil to deflect forces relative to an impact from the boat. Godbersen U.S. Pat. No. 6,554,533 discloses a dry dock or boat lift using hydraulics. Here, there is a framework which rests on the ground, which proposes a hydraulic means of lifting the boat on a four-post rectangular frame structure. The movable framework is operatively connected to a pulley and cable suspension system to raise and lower the suspension system secured on the four vertical posts.
While these devices are useful in themselves and, to some degree, recognize the problems that a boater may have in piloting a boat into a docking area, they do not recognize the problem for standard boat lifts caused by wind current, waves, or wakes like those that might be seen in a river or along the intracoastal waterway, nor do they suggest a system which can be used on existing boat lifts to solve the problem created by current, wind and wave action, and wakes for an individual boater trying to use a boat lift to get a boat in or out of the water.